The importance of the pose in three-dimensional imaging of the ptotic breast

Reliability and Measurement Error of Breast Volume Calculation Using Three-Dimensional Surface Imaging

Background: Breast lymphedema after breast cancer is challenging to quantify. Three-dimensional (3D) surface imaging is one available technique to measure breast volume, however, the measurement properties of available software programs have not been fully determined. The aim of this study was to determine equivalency of measurements with two software programs as well as reliability, standard error of measurement (SEM), and smallest detectable change (SDC). Methods and Results: Retrospective three-dimensional surface imaging (3D-SI) of 100 breasts taken before or after breast conserving surgery for breast cancer were retrieved for reliability analysis. Three assessors followed a standardized measurement technique using two software programs, Vectra^® 3D Analysis Module (VAM) and Breast Sculptor^®. Mean breast volume was 489.9 ± 206 cc using VAM and 480.1 ± 229.1 cc using Breast Sculptor. Lin's concordance showed poor agreement between programs (0.81-0.88). Measurements using VAM had excellent intra- and inter-rater reliability with SEM = 4.1% for one assessor and 8.7% for multiple assessors. Breast Sculptor also had excellent intra-rater and substantial inter-rater reliability but the SEM was much larger at 14.5% (intra-rater) and 19.1% (inter-rater). The SDC value was lowest for VAM and a single rater with 56 cc indicating a meaningful change beyond measurement error. Conclusion: Breast volume measurements captured with 3D-SI using VECTRA-XT are highly reliable, but the volumes, SEM, and SDC varied between the two software programs. Measurement error was lowest with VAM software. Although the usefulness of VECTRA-XT and VAM software to detect change in breast volume is promising, further solutions to reduce measurement error are required to improve clinical utility to measure breast lymphedema.

Menstrual Cycle-Related Fluctuations in Breast Volume Measured Using Three-Dimensional Imaging: Implications for Volumetric Evaluation in Breast Augmentation

BACKGROUND

Breast volume is a key parameter of breast measurement in breast augmentation. However, the correlation between menstrual cycle phases and variation in breast volume has not been well studied.

METHODS

Young female patients with regular menstrual cycles underwent eight three-dimensional imaging scans during a single menstrual cycle from November 2017 to January 2018. Breast volumetric difference at each timepoint and basic breast volume were measured for each subject. Preovulatory phase and postovulatory phase values were compared using an unpaired t test. A Pearson's linear correlated analysis was performed to identify the correlation between the basic breast volume and maximum range of breast volumetric difference during the menstrual cycle.

RESULTS

Thirteen patients (26 breasts) met the inclusion criteria. During the menstrual cycle, the breast volumetric difference showed first a rising trend followed by a fall. A significant difference in the breast volumetric difference between the preovulatory phase and postovulatory phase (- 19.6 ± 2.1 ml pre-ovulation vs. - 6.9 ± 3.3 ml post-ovulation, p = 0.002) was noted. There was a positive linear association between breast volume and maximum range of breast volumetric difference when a Pearson correlation was used (r = 0.45, p = 0.021).

CONCLUSIONS

The breast volume fluctuates during the menstrual cycle, and there is a significant difference between the preovulatory phase and postovulatory phase for breast volumetric change. The influence of the menstrual cycle on breast volume should be taken into consideration by plastic surgeons performing breast augmentation.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Chances and limitations of a low-cost mobile 3D scanner for breast imaging in comparison to an established 3D photogrammetric system

BACKGROUND

In search of new possibilities in 3D surface imaging, several nonmedical scanning systems have been assessed for their implementation in plastic surgery. The aim of this study was to compare a new affordable 3D imaging consumer product with an established medical 3D imaging system for objective 3D breast imaging.

METHOD

We compared a low-cost mobile, handheld scanner against an established medical 3D surface imaging system. Forty-two female patients who underwent different types of breast surgery were captured in a 3D view with both devices. Digital breast measurement, volume measurement, and breast surface-to-surface analysis were done using Mirror software. Repeatability was assessed by repeated 3D scans of the torso and surface-to-surface analysis.

RESULTS

Digital breast measurement showed low differences with good-to-excellent correlation between both devices. Mean breast volume difference was small (-5.11 ± 32.10 mL) within the 95% limits of agreement. Surface-to-surface analysis yielded a higher surface deviation in the lower breast quadrants (1.62 ± 0.80 mm root mean square [RMS] error and 1.81 ± 0.88 mm RMS error) than in the upper breast quadrants. Repeatability was satisfactory with a mean of 0.636 ± 0.279 mm RMS error.

CONCLUSION

Affordable mobile surface scanners may offer new perspectives in the future for 3D breast imaging. Although surface acquisition was sufficient for breast measurements in comparison to an established system, the lack of appropriate medical software for patient consultation next to moderate texture quality needs to be improved for wider acceptance in plastic surgery.

Weighted regularized statistical shape space projection for breast 3D model reconstruction

The use of 3D imaging has increased as a practical and useful tool for plastic and aesthetic surgery planning. Specifically, the possibility of representing the patient breast anatomy in a 3D shape and simulate aesthetic or plastic procedures is a great tool for communication between surgeon and patient during surgery planning. For the purpose of obtaining the specific 3D model of the breast of a patient, model-based reconstruction methods can be used. In particular, 3D morphable models (3DMM) are a robust and widely used method to perform 3D reconstruction. However, if additional prior information (i.e., known landmarks) is combined with the 3DMM statistical model, shape constraints can be imposed to improve the 3DMM fitting accuracy. In this paper, we present a framework to fit a 3DMM of the breast to two possible inputs: 2D photos and 3D point clouds (scans). Our method consists in a Weighted Regularized (WR) projection into the shape space. The contribution of each point in the 3DMM shape is weighted allowing to assign more relevance to those points that we want to impose as constraints. Our method is applied at multiple stages of the 3D reconstruction process. Firstly, it can be used to obtain a 3DMM initialization from a sparse set of 3D points. Additionally, we embed our method in the 3DMM fitting process in which more reliable or already known 3D points or regions of points, can be weighted in order to preserve their shape information. The proposed method has been tested in two different input settings: scans and 2D pictures assessing both reconstruction frameworks with very positive results.

Preoperative implant selection for unilateral breast reconstruction using 3D imaging with the Microsoft Kinect sensor

AIMS

This study aimed to investigate whether breast volume measured preoperatively using a Kinect 3D sensor could be used to determine the most appropriate implant size for reconstruction.

METHODS

Ten patients underwent 3D imaging before and after unilateral implant-based reconstruction. Imaging used seven configurations, varying patient pose and Kinect location, which were compared regarding suitability for volume measurement. Four methods of defining the breast boundary for automated volume calculation were compared, and repeatability assessed over five repetitions.

RESULTS

The most repeatable breast boundary annotation used an ellipse to track the inframammary fold and a plane describing the chest wall (coefficient of repeatability: 70 ml). The most reproducible imaging position comparing pre- and postoperative volume measurement of the healthy breast was achieved for the sitting patient with elevated arms and Kinect centrally positioned (coefficient of repeatability: 141 ml). Optimal implant volume was calculated by correcting used implant volume by the observed postoperative asymmetry. It was possible to predict implant size using a linear model derived from preoperative volume measurement of the healthy breast (coefficient of determination R² = 0.78, standard error of prediction 120 ml). Mastectomy specimen weight and experienced surgeons' choice showed similar predictive ability (both: R² = 0.74, standard error: 141/142 ml). A leave one-out validation showed that in 61% of cases, 3D imaging could predict implant volume to within 10%; however for 17% of cases it was >30%.

CONCLUSION

This technology has the potential to facilitate reconstruction surgery planning and implant procurement to maximise symmetry after unilateral reconstruction.

An analysis of pose in 3D stereophotogrammetry of the breast

BACKGROUND

Volume of the breast can be objectively measured by three-dimensional (3D) photographs. This study describes the analysis of three different positions of the patient in image acquisition, in order to find the best pose for reproducible 3D photographs of the breasts.

METHOD

Twenty-four patients were included between February and September 2014 in a consecutive way. Data were collected prospectively. 3D photographs were acquired using a stereophotogrammetry system. Images were taken twice in three different positions (arms behind the back, arms placed on the hips and arms horizontally placed). Surface based matching was applied and the absolute mean distance between the surfaces of both 3D models of the same position was calculated. This difference measure represents the similarity of the photographs.

RESULTS

Univariate ANOVA showed a significant difference in distance between the three positions (sum of squares 1.12, p < 0.001). The horizontal position presented the lowest absolute mean distance (0.45 mm). Additional post hoc multiple comparisons analysis revealed a statistically significant difference between the distances of horizontal and back position (-0.22 mm, p < 0.001) and of back and hip position (0.13 mm, p = 0.009), with better results of the horizontal and hip positions, respectively.

CONCLUSION

Standardization of 3D acquisition in pre- and postoperative breast imaging could improve imaging reproducibility. Based on the results of this study, we recommend a pose with the arms in a horizontal position.

The accuracy of breast volume measurement methods: A systematic review

Breast volume is a key metric in breast surgery and there are a number of different methods which measure it. However, a lack of knowledge regarding a method's accuracy and comparability has made it difficult to establish a clinical standard. We have performed a systematic review of the literature to examine the various techniques for measurement of breast volume and to assess their accuracy and usefulness in clinical practice. Each of the fifteen studies we identified had more than ten live participants and assessed volume measurement accuracy using a gold-standard based on the volume, or mass, of a mastectomy specimen. Many of the studies from this review report large (>200 ml) uncertainty in breast volume and many fail to assess measurement accuracy using appropriate statistical tools. Of the methods assessed, MRI scanning consistently demonstrated the highest accuracy with three studies reporting errors lower than 10% for small (250 ml), medium (500 ml) and large (1000 ml) breasts. However, as a high-cost, non-routine assessment other methods may be more appropriate.

Multi-view stereophotogrammetry for post-mastectomy breast reconstruction

A multi-view three-dimensional stereophotogrammetry system was developed to capture 3D shape of breasts for breast cancer patients. The patients had received immediate unilateral breast reconstruction after mastectomy by the extended latissimus dorsi flap and without contralateral surgery. In order to capture the whole breast shape including the inframammary fold, the patients were introduced to the imaging room and leaned over the imaging rig to open up the inframammary fold and to expose the entire area of each breast. The imaging system consisted of eight high-resolution ([Formula: see text] pixels) digital cameras and four flash units. The cameras were arranged in four stereo pairs from four different view angles to cover the whole surface of the breasts. The system calibration was carried out ahead of every capture session, and the stereo images were matched to generate four range images to be integrated using an elastic model proposed. A watertight breast mesh model was reconstructed to measure the volume of the breast captured. The accuracy of using the developed multi-view stereophotogrammetry system for breast volume measurement was 11.12cc with SEM 7.74cc, comparing to the measurements of the water displacement method. It was concluded that the 3D stereophotogrammetry image system developed was more reliable than the method of water displacement.

Objective breast volume, shape and surface area assessment: a systematic review of breast measurement methods

BACKGROUND

There are many methods of measuring the breast and their clinical applications are well described in the literature. However, there has been no attempt to compare these various methods to allow the user to have a broad overview of the subject. The authors have attempted to summarise all the available methods to measure the breast in this article to provide a useful reference for all.

METHODS

A comprehensive literature search of PubMed was performed, and the resulting articles were screened and reviewed. The data regarding the methods' mechanism, reliability, time and cost were evaluated and compared.

RESULTS

A total of 74 articles dating from 1970 to 2013 were included in this study. All of the methods can be classified into those that measure (1) volume, (2) shape and (3) surface area. Each category consists of several methods that work through different mechanisms and they vary in their reliability and feasibility. Based on their mechanism, the volume measurement methods were further grouped into the natural shape methods, the stereological method, the geometrical methods and the mathematical modelling method.

CONCLUSIONS

More objective breast evaluation can be achieved if all three dimensions (volume, shape and surface area) are considered. In the volume measurements, 3D modelling and the MRI are the most reliable tools. Linear measurement (geometry) and mathematical modelling are less accurate but are more economical. In the shape measurements, besides the traditional linear measurement, 3D methods that can deliver colour-coded maps and Swanson's 2D photographic measurement system are capable of depicting and tracking breast shape changes after surgery. Although the surface area metric has not been used extensively, it has potential in clinical and research applications.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.